The present invention relates to a combustion tube for an induction furnace employed in an analytical instrument.
Quartz combustion tubes have been used in connection with combustion furnaces for many years for enclosing a sample for the analysis of elements, such as carbon or sulfur. One commercially available analyzer is Model No. CS600, available from Leco Corporation of St. Joseph, Mich. Such an analyzer uses a quartz combustion tube which is typically used to maintain a pressurized oxygen-rich environment for the combustion of a sample in a ceramic crucible held within an induction coil surrounding the combustion tube. U.S. Pat. Nos. 2,809,100, 3,923,464, and 4,234,541 are examples of systems employing such quartz combustion tubes. The disclosures of these patents are incorporated herein by reference.
During the combustion process, byproducts of combustion frequently cause deposits on the combustion tube. The quartz tube must be cleaned and eventually replaced to maintain the accuracy of sample results. The mounting of a combustion tube in existing furnaces equipped with an auto cleaner is both time consuming and cumbersome, requiring that fluid fittings and electrical connections be removed and the auto-cleaner device removed from the combustion tube area of the furnace. The combustion tube is removed from the top of the furnace housing once the disassembly has been completed. Once a new combustion tube has been installed, the furnace has to be reassembled, frequently including the connection of fluid couplings which can lead to leaks in the system if not properly accomplished. Thus, the maintenance, removal and replacement of combustion tubes in existing furnaces is difficult, time consuming, and leads to downtime for the operation of an analyzer.
Accordingly, there exists a need for an improved combustion tube for use in an analytical combustion furnace which can be readily accessed without disconnecting fluid fittings, auto-cleaners, or the like from the furnace assembly.